Rotary furnace

ABSTRACT

A rotary tubular furnace having a cooling zone comprising an array of passages for conveying the furnace charge to a discharge station. The passages are disposed around the furnace and extend generally parallel to its axis from the furnace discharge end. Conical sections oriented with axes generally parallel and offset from each other are coupled in tandem to form passages which retard the issuance of the charge and enhance its cooling.

United States Patent [72] Inventors Otto l-leinemann Ennigerloh; WernerSch'o'bler, Ahler, both of Germany [21] Appl. No. 55,634

[22] Filed July 17, 1970 [45] Patented Nov. 9, 1971 [73] AssigneePolysium AG Neubeckum, Germany [32] Priority Aug. 22, i969 [3 3 Germany[54] ROTARY FURNACE 8 Claims, 7 Drawing Figs.

[52] US. Cl 263/32 C, 165/88 [51 1 Int. Cl 4. F27b 7/38 [50] Field ofSearch 263/32 R. 32 C; 165/88 156] References Cited UNITED STATESPATENTS 3,502,139 3/1970 Anderson 263/32 X Primary Examiner-J0hn J.Camby Attorney-Wilson & Fraser ABSTRACT: A rotary tubular furnace havinga cooling zone comprising an array of passages for conveying the furnacecharge to a discharge station. The passages are disposed around thefurnace and extend generally parallel to its axis from the furnacedischarge end. Conical sections oriented with axes generally paralleland oflset from each other are coupled in tandem to form passages whichretard the issuance of the charge and enhance its cooling.

PATENTEDHUV 9 ISYI 3,618,915

SHEET 1 OF 4 INVENTORS OTTO HEINEMANN WERNER SCH'O'BLER' LdLiwa-m1AM!!!) ATTORNEYS PATENTEDNOV 9 IQYI 3,618,915

SHEET 2 OF 4 INVIIN'IORS OTTO HEINEMANN WERNER SCHOBLER BYI (UM 41MATTORNEYS INVENTORS OT TO HEINEMANN WERNER SCI-ICBLER L M 5 7 5L040),

ATTORNEYS PATENTEUHuv 9 ml 7 3,618,915

SHEET 4 BF 4 Z5 Z2 ,3; I 1 x INVIIN'I'ORS OTTO HEINEMANN WERNER SCHOBLERBY:

ATTORNEYS ROTARYFURNACE FIELD OF THE INVENTION This invention relates torotary tubular furnaces and more particularly to such furnaces havingcooling passages from the outlet for cooling the furnace charge.

BACKGROUND OF THE INVENTION Heretofore, rotary tubular furnaces havebeen provided with a plurality of cooling passages disposed in satelliterelationship on the periphery of the furnace tube shell. These passageshave been of a conical form expanded in the direction of material flowand have been connected to the outlet of the rotary tubular furnace byfeedpipes. In order to control the movement of the material to becooled, it has been known to provide the single-piece conical coolingpassages with internal bafiels. Such coolers pass the material throughthe cooling passages too quickly so that the material is not cooledsufficiently.

SUMMARY OF THE INVENTION According to the invention rotary tubularfurnaces are provided with a plurality of cooling pipes wherein eachcooling pipe comprises at least two conical pipe portions disposed inaxial sequence and offset in parallel from each other by at least thedifference between the major and minor cone radii.

The object of the invention is to form the cooler for a rotary tubularfurnace of the type mentioned in such manner that the period spent bythe material in the cooling pipes is sufiicient for intensive cooling.

This type of cooling pipe construction in accordance with the inventionmeans that a single straight line inclined towards the cooling pipeoutlet or a step dropping towards the outlet is only formed at thetransition or connecting points between the individual conical pipeportions during part of each rotation of the rotary tubular furnace.During the remaining part of each rotation however, steps rising towardsthe outlets are present between the succeeding individual conical pipeportions. In this manner the movement of the material through thecooling pipe is retarded during a considerable part of the rotation ofthe tubular furnace, and only favored once during each rotation. In thismanner the desired prolongation of the period spent by the material inthe cooling pipes is achieved. The desired duration can be influenced bythe choice of a suitable axially parallel offsetting of the conical pipeportions. In this manner it is possible to adapt to the particularobjective for which the furnace is used.

In order to achieve reliable feeding of material to the cooling pipeoutlet, the conical inclination of the conical pipe portions should beat least twice as great asthe inclination of the rotary furnace, andpreferably twice to four times as great.

It is also desirable for the axes of the conical pipe portions of allthe cooling pipes to lie on an imaginary cylindrical sur face concentricwith the rotary furnace. A construction ofthis type in accordance withthe invention gives a compact design, economical of space, for therotary furnace and cooler.

DESCRIPTION OF THE DRAWINGS These and further details of the inventionwill appear from the following description of certain embodiments shownin the drawings. In these:

FIG. 1 is a schematic longitudinal view of a first embodiment accordingto the invention;

FIG. 2 is a cross section of the line II-II of FIG. 1;

FIG. 3 is a schematic longitudinal view of a slightly altered secondembodiment; and

FIGS. 4-7 are schematic longitudinal view and cross sections of twofurther embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show a rotarytubular furnace 1 whose cooler comprises a number of cooling pipes 2, 3,4 and 5 disposed in satellite manner on the periphery of and extendingback along the length of the rotary furnace, these pipes being conicallyexpanded in the direction of material flow (arrow 6). The inlets of thecooling pipes are connected to the outlet 11 of the rotary furnace l bymeans of feedpipes 7, 8, 9, 10.

Each of the cooling pipes 2, 3, 4 and 5 shown in the drawing consists ofthree conical pipe portions 2a-2c, Sal-3c, 4a-4cand 5a-5c disposed inaxial sequence,said portions being in this embodiment axially paralleloffset from each other by the difference between the major and minorcone radii, wherein the conical inclination S of all the pipe portions(e.g. 3a) is at least twice the inclination S of the rotary furnace 1relative to the horizontal H. The end faces of the conical pipe portionslie in planes which run perpendicular to the longitudinal axes of thecorresponding pipe portions. In order to produce a compact constructionof the rotary furnace 1, the axes of the conical pipe portions 2a-5c ofall the cooling pipes 2-5 lie on an imaginary cylindrical surface 12concentric with the rotary furnace 1. This furnace l is surrounded by anannular outlet housing 13 wherein terminate the outlet ends of all thecooling pipes 2-5. The outlet sides of the cooling pipes are thusdirected towards the inlet end of the rotary furnace l, which alsocontributes to the spatial economy of the furnace construction. Whilethe cooling pipe 2-5 are fixedly attached to the rotary furnace l, thecommon outlet housing 13 can be made stationary.

In the operating condition of rotary furnace I, the heated material fromthe furnace outlet moves for the purpose of cooling through thefeedpipes 7-10 into the inlets of the cooling pipes 2-5 which constitutethe cooler. Due to the rotary movement of the furnace l and thesufficiently large'conical inclination S of the individual pipe portions2a 5c, the material is fed in each conical pipe portion to the end facewith the large diameter. The passage of material from one conical pipeportion e.g. with the index letter a to the next (e.g. with thereference letter b) is either favored or else hindered to a greater orlesser degree, depending on the rotational position of the furnace 1.

If the embodiment in FIGS. 1 and 2 is considered, it readily will benoted that with the construction of cooling pipes 2-5 in accordance withthe invention, the connecting points between theindividual conical pipeportions fonn a single straight line inclined towards the cooling pipeoutlet for only a small portion of each rotation of the furnace. Thecooling pipe 3 then finds itself in a rotational position wherein thematerial being cooled is fed from one conical pipe portion to the nextas though on an inclined shoot. Rotary movement in the direction ofarrow 14 means that this position of cooling pipe 3 favorable to theconveyance of the material ceases again after a brief duration. For thematerial, whose position in the cooling pipe is also continuouslychanged by the rotary motion, there are now steps rising towards thecooling pipe outlet, these being most marked in the position of coolingpipe 5. In positions with steps rising towards the cooling pipe outlet,i.e. during the major part of each revolution, only a small proportion,or even none, of the material, depending on the amount in the coolingpipe, can be passed from one conical pipe portion into the next. Thisensures that the material will stay in the cooling pipes for a longperiod, and this leads to intensive cooling.

FIG. 3 shows a form of the invention slightly varied from the firstembodiment. The cooling pipes 15, 16 and 17 are disposed in this caseexactly as in the first embodiment. The difference lies in theconstruction of the pipes themselves. They consist of conical pipeportions whereof those end faces do not terminate in the outlet housing13 lie in planes which run obliquely to the longitudinal axis of thecorresponding pipe portion. This means that there is an obtuse anglebetween the main surface and the end face at the points in theindividual pipe portions where the major part of the material is held up(i.e. at the points where the step is highest). This simple constructionprovided by the invention prevents agglomerations of material atpositions where this is a special danger.

The cooling pipes 18, 19, 20 and 21 of the rotary tubular furnace 1shown in FIGS. 4 and 5 differ slightly in shape from those seen in FIGS.1 and 2, in that the conical pipe portions are axially parallel andoffset by approximately the size of the minor diameter of the cone.Since particularly large steps are produced in this way, this embodimentis most generally chosen when the material is required to stay anespecially long time in the cooling pipes.

Finally, similar advantages are also provided by the embodiment shown inFIGS. 6 and 7. Here the conical portions 22, 23 and 24 of the coolingpipes are offset by so much (i.e. by about the total of the major andminor cone radii) that transition pieces, preferably conical( (e.g. 25and 26) are provided between the individual pipe portions, and alsochutes (e.g 27 and 28) dropping in the direction of feed. Thisembodiment also provides a particularly long cooling path in theindividual cooling pipes, with effective use of the space available atthe periphery of the rotary furnace.

We claim:

1. A rotary tubular furnace with a cooler comprising a number of coolingpipes disposed in satellite manner on the periphery of the tubularfurnace, said pipes conically widening in the direction of materialflow, and having their inlet connected by a feedpipe to the outlet ofthe rotary tubular furnace, characterized in that each cooling pipecomprises at least two conical pipe portions disposed in axial sequenceand having their axes offset in parallel from each other by at least thedifierence between the major and minor cone radii.

2. A rotary tubular furnace as in claim 1 wherein the rotary tubularfurnace is inclined, characterized in that the conical inclination ofthe conical pipe portion is at least twice as great as the inclinationof the rotary tubular furnace.

3. A rotary tubular furnace as in claim 1 wherein the rotary tubularfurnace is inclined, characterized in that the conical inclination ofthe conical pipe portion is two to four times as great as theinclination of the rotary tubular furnace.

4. A rotary tubular furnace as in claim 1, characterized in that theaxes of the conical pipe portions of all the cooling pipes lie on thesurface of an imaginary cylinder concentric with the rotary tubularfurnace.

5. A rotary tubular furnace as in claim 1 wherein said cooling pipeshave outlets in an annular array around the axis of said furnace andincluding a common annular outlet housing surrounding the rotary tubularfurnace concentric with the outlets of the cooling pipes.

6. A rotary tubular furnace as in claim 1, characterized in that eachend face of a conical pipe portion lies in a plane runningperpendicularly to the longitudinal axis of the pipe portion.

7. A rotary tubular furnace as in claim 1, characterized in that atleast some end faces of the conical pipe portions lie in planes whichare parallel to each other and inclined to the longitudinal axis of theconical pipe portions.

8. A tubular furnace as in claim I, characterized in that the conicalpipe portions are axially parallel and offset from each other by atleast the total of the major and minor cone radii, and in that conicaltransition pieces are provided at the connection points between theconical pipe portions, together with chutes inclined in the direction offeed of the material.

i t i it

1. A rotary tubular furnace with a cooler comprising a number of coolingpipes disposed in satellite manner on the periphery of the tubularfurnace, said pipes conically widening in the direction of materialflow, and having their inlet connected by a feedpipe to the outlet ofthe rotary tubular furnace, characterized in that each cooling pipecomprises at least two conical pipe portions disposed in axial sequenceand having their axes offset in parallel from each other by at least thedifference between the major and minor cone radii.
 2. A rotary tubularfurnace as in claim 1 wherein the rotary tubular furnace is inclined,characterized in that the conical inclination of the conical pipeportion is at least twice as great as the inclination of the rotarytubular furnace.
 3. A rotary tubular furnace as in claim 1 wherein therotary tubular furnace is inclined, characterized in that the conicalinclination of the conical pipe portion is two to four times as great asthe inclination of the rotary tubular furnace.
 4. A rotary tubularfurnace as in claim 1, characterized in that the axes of the conicalpipe portions of all the cooling pipes lie on the surface of animaginary cylinder concentric with the rotary tubular furnace.
 5. Arotary tubular furnace as in claim 1 wherein said cooling pipes haveoutlets in an annular array around the axis of said furnace andincluding a common annular outlet housing surrounding the rotary tubularfurnace concentric with the outlets of the cooling pipes.
 6. A rotarytubular furnace as in claim 1, characterized in that each end face of aconical pipe portion lies in a plane running perpendicularly to thelongitudinal axis of the pipe portion.
 7. A rotary tubular furnace as inclaim 1, characterized in that at least some end faces of the conicalpipe portions lie in planes which are parallel to each other andinclined to tHe longitudinal axis of the conical pipe portions.
 8. Atubular furnace as in claim 1, characterized in that the conical pipeportions are axially parallel and offset from each other by at least thetotal of the major and minor cone radii, and in that conical transitionpieces are provided at the connection points between the conical pipeportions, together with chutes inclined in the direction of feed of thematerial.